e = 2.7 1828 1828459

The first mention of the constant e is a table in the appendix of John Napier's logarithmic works published in 16 18. But it didn't record this constant, only a list of natural logarithms calculated from it, which is generally believed to be made by William Oughtred. It was Jacob Bernoulli who first thought that E was a constant. He tried to calculate the value of the following formula:

(1+ 1/n), and find the limit when its n tends to infinity.

The earliest known uses of the constant e are 1690 and 169 1 year, which is represented by B. In 1727, Euler began to use e to represent this constant. E was first used in publications, and it was Euler Mechanics in 1736. Although some researchers later used the letter c, e was more commonly used and eventually became the standard.

The reason why E is used is really unknown, but it may be because E is the first letter of the word "index". Another view is that A, B, C and D have other common usages, and E is the first available letter.

However, it is unlikely that Euler chose this letter because it is the initials of his own name, because he is a very modest person and always properly affirms the work of others.